In a manufacturing application, a plurality of load devices may be disposed in parallel on a common supply. If one of the devices is not functioning properly, the manufacturing application may be affected. Accordingly, it is desirable to monitor the load devices for their functionality and provide a signal indicative of an abnormal operation condition.
U.S. Pat. No. 5,001,465 relates to a plurality of continuously operating proximity sensors mounted upon a crane boom which detect a dangerous condition. Filtering removes noise and harmonics from an output signal, which if greater than a desired voltage, triggers an alarm.
U.S. Pat. No. 4,316,187 is directed to an apparatus for verifying the load rating of an active alternating current distribution circuit. Averaging and rectification of the alternating current are conducted.
While these references may have achieved a certain degree of success in their particular application, the systems apply averaging and long time delays to the sensing process. This is unsuitable for intermittent duty applications, particularly when an instantaneous loss of one or more of the load devices is difficult to detect when only a single AC cycle of current is applied using a single sensing conductor.
Accordingly, there exists a need for a monitoring apparatus and method directed to intermittent duty applications wherein a fast, continuous response is provided without use of averaging or other data collection techniques.